1. Field of the Invention
The present invention relates generally to the communication field, and more particularly, to a method for updating location information of User Equipment (UE) under an enhanced network.
2. Description of the Related Art
A system structure of System Architecture Evolution (SAE) is illustrated in FIG. 1.
A UE 101 is a terminal device for receiving data.
An Evolved Universal Terrestrial Radio Access Network (EUTRAN) 102 is a wireless access network in evolution system SAE, also referred to as Evolved Node B or eNodeB (eNB), which provides Long Term Evolution (LTE) mobile phones with an interface for accessing a wireless network. The EUTRAN 102 connects to a Mobile Management Entity (MME) 103 and a user plane entity Serving Gateway 104 via an interface S1.
MME 103 is used for managing mobile context of the UE 101, session context, and saving user information on security.
The Serving Gateway (S-GW) 104 primarily provides a function of user plane. An interface S1-MME is responsible for establishing a radio access bearer, forwarding messages from the UE 101 to the MME 103 through the wireless access network. The combined function of the MME 103 and the Serving Gateway 104 is similar to that of an original General Packet Radio Service (GPRS) Supporting Node (SGSN) 106. It is possible for both the MME 103 and the Serving Gateway 104 to be located at the same physical entity.
Packet Data Network (PDN) Gateway 105 is used for functions such as accounting, legally monitoring, etc. It is possible for both the Serving Gateway 104 and the PDN Gateway 105 to be located at the same physical entity. The SGSN 106 provides routing for data transmissions in an existing Universal Mobile Telecommunications System (UMTS). The existing SGSN finds corresponding Gateway (GPRS) Supporting Nodes (GGSN) according to Access Point Name (APN).
Home Subscription Subsystem (HSS) 107 is used for storing user information such as current location of the UE 101, an address of the serving node, security related information for the user, an activated Packet Data Protocol (PDP) context for the UE, etc.
Policy and Charging Rules Function (PCRF) 108 provides Quality of Service (QoS0 policy and accounting rules through an interface S7.
In general, a user data stream is transmitted to the Serving Gateway 104 through the PDN Gateway 105. Then, via a GPRS Tunnel Protocol (GTP) channel, data is sent by the Serving Gateway 104 to the ENB 102 in which the UE 101 is located, and the data is sent by the ENB 102 to the UE 101.
FIG. 2 is a diagram illustrating a structure of an S1 interface in the SAE where the MME is a mobile management entity and the S-GW is a data plane entity in an evolved core network. Each ENB connects with several MMEs in an MME pool. Each ENB connects with several S-GWs in the S-GW Pool. The interface between ENBs is called an X2 interface.
In order to avoid transmitting an uplink signaling, such as a Tracking Area (TA) update message, by the UE in an idle mode when the UE frequently moves between ENBs, a multi-TA list is used. When the UE is under a TA updated process, the MME notifies the UE of adjacent multi-TA lists that the UE can access via TA update response messages. The UE saves such TA lists upon the receipt. Thus, UE will not initiate TA update process when moving among several TAs.